Aggregate results in resource estimator across multiple runs

src/Simulation/EntryPointDriver.Tests/Tests.fs

@@ -474,15 +474,15 @@ let ``Shadows --shots`` () =
 
 // The expected output from the resources estimator.
 let private resourceSummary =
-    "Metric          Sum
-     CNOT            0
-     QubitClifford   1
-     R               0
-     Measure         1
-     T               0
-     Depth           0
-     Width           1
-     BorrowedWidth   0"
+    "Metric          Sum Max
+     CNOT            0   0
+     QubitClifford   1   1
+     R               0   0
+     Measure         1   1
+     T               0   0
+     Depth           0   0
+     Width           1   1
+     BorrowedWidth   0   0"
 
 [<Fact>]
 let ``Supports QuantumSimulator`` () =

src/Simulation/Simulators.Tests/Circuits/ResourcesEstimator.qs

@@ -17,6 +17,27 @@ namespace Microsoft.Quantum.Simulation.Simulators.Tests
         }
     }
 
+    // When multiple operations are traced by resource estimator,
+    // it should report cumulative statistics in the end.
+    operation Operation_1_of_2() : Unit
+    {
+        using ((a, b) = (Qubit(), Qubit())) {
+            H(a);
+            CNOT(a, b);
+            T(b);
+        }
+    }
+    operation Operation_2_of_2() : Result
+    {
+        using ((a, b, c) = (Qubit(), Qubit(), Qubit())) {
+            X(a);
+            CNOT(a, b);
+            Rx(0.42, b);
+            CNOT(b, c);
+            return M(c);
+        }
+    }
+
     // Tests for Depth and Width lower bounds
     operation DepthDifferentQubits () : Unit
     {

src/Simulation/Simulators.Tests/ResourcesEstimatorTests.cs

@@ -2,9 +2,8 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Generic;
 using System.Linq;
-using System.Text;
+using System.Data;
 using Microsoft.Quantum.Simulation.QCTraceSimulatorRuntime;
 using Xunit;
 
@@ -95,10 +94,10 @@ public void ToTSVTest()
 
             var cols = rows[0].Split('\t');
             Assert.Equal("Metric", cols[0].Trim());
-            Assert.Equal(2, cols.Length);
+            Assert.Equal(3, cols.Length);
 
             var cliffords = rows.First(r => r.StartsWith("QubitClifford")).Split('\t');
-            Assert.Equal(2, cliffords.Length);
+            Assert.Equal(3, cliffords.Length);
             Assert.Equal("2", cliffords[1]);
         }
 
@@ -138,5 +137,43 @@ public void DepthVersusWidthTest()
             Assert.Equal(1.0, data.Rows.Find("Width")["Sum"]);
             Assert.Equal(1.0, data.Rows.Find("Depth")["Sum"]);
         }
+
+        /// <summary>
+        /// Verifies that for multiple separately traced operations, the final
+        /// statistics are cumulative.
+        /// </summary>
+        [Fact]
+        public void VerifyTracingMultipleOperationsTest()
+        {
+            ResourcesEstimator sim = new ResourcesEstimator();
+
+            Operation_1_of_2.Run(sim).Wait();
+            DataTable data1 = sim.Data;
+
+            Assert.Equal(1.0, data1.Rows.Find("CNOT")["Sum"]);
+            Assert.Equal(1.0, data1.Rows.Find("QubitClifford")["Sum"]);
+            Assert.Equal(1.0, data1.Rows.Find("T")["Sum"]);
+            Assert.Equal(0.0, data1.Rows.Find("R")["Sum"]);
+            Assert.Equal(0.0, data1.Rows.Find("Measure")["Sum"]);
+            Assert.Equal(2.0, data1.Rows.Find("Width")["Sum"]);
+
+            Operation_2_of_2.Run(sim).Wait();
+            DataTable data2 = sim.Data;
+
+            // Aggregated stats for both operations.
+            Assert.Equal(1.0 + 2.0, data2.Rows.Find("CNOT")["Sum"]);
+            Assert.Equal(1.0 + 1.0, data2.Rows.Find("QubitClifford")["Sum"]);
+            Assert.Equal(1.0 + 0.0, data2.Rows.Find("T")["Sum"]);
+            Assert.Equal(0.0 + 1.0, data2.Rows.Find("R")["Sum"]);
+            Assert.Equal(0.0 + 1.0, data2.Rows.Find("Measure")["Sum"]);
+            Assert.Equal(2.0 + 3.0, data2.Rows.Find("Width")["Sum"]);
+            Assert.Equal(System.Math.Max(2.0, 3.0), data2.Rows.Find("Width")["Max"]);
+
+            // Run again to confirm two operations isn't the limit!
+            VerySimpleEstimate.Run(sim).Wait();
+            DataTable data3 = sim.Data;
+            Assert.Equal(2.0 + 3.0 + 3.0, data3.Rows.Find("Width")["Sum"]);
+            Assert.Equal(3.0, data3.Rows.Find("Width")["Max"]);
+        }
     }
 }

src/Simulation/Simulators/ResourcesEstimator/ResourcesEstimator.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Generic;
 using System.Data;
 using System.Diagnostics;
 using System.Linq;
@@ -113,6 +112,7 @@ public virtual DataTable Data
 
                 table.Columns.Add(new DataColumn { DataType = typeof(string), ColumnName = "Metric" });
                 table.Columns.Add(new DataColumn { DataType = typeof(double), ColumnName = "Sum" });
+                table.Columns.Add(new DataColumn { DataType = typeof(double), ColumnName = "Max" });
                 table.PrimaryKey = new DataColumn[] { table.Columns[0] };
 
                 foreach (var l in CoreConfig.Listeners)
@@ -121,24 +121,31 @@ public virtual DataTable Data
                     if (l is ICallGraphStatistics collector)
                     {
                         var results = collector.Results.ToTable();
-                        Debug.Assert(results.rows.Count() == 1);
                         Debug.Assert(results.keyColumnNames.Length > 2 && results.keyColumnNames[2] == "Caller");
 
-                        var root = results.rows.FirstOrDefault(r => r.KeyRow[2] == CallGraphEdge.CallGraphRootHashed);
-
+                        var roots = results.rows.Where(r => r.KeyRow[2] == CallGraphEdge.CallGraphRootHashed);
                         var s_idx = Array.FindIndex(results.statisticsNames, n => n == "Sum");
 
                         for (var m_idx = 0; m_idx < results.metricNames.Length; m_idx++)
                         {
                             var label = GetMetricLabel(results.metricNames[m_idx]);
                             if (label == null) continue;
 
-                            var row = table.NewRow();
+                            DataRow row = table.NewRow();
                             row["Metric"] = label;
 
                             if (m_idx >= 0 && s_idx >= 0)
-                            {
-                                row["Sum"] = root.DataRow[m_idx, s_idx];
+                            {
+                                Double sum = 0;
+                                Double max = 0; // all our metrics are positive
+                                foreach (var r in roots)
+                                {
+                                    Double metric_value = r.DataRow[m_idx, s_idx];
+                                    sum += metric_value;
+                                    max = System.Math.Max(max, metric_value);
+                                }
+                                row["Sum"] = sum;
+                                row["Max"] = max;
                             }
 
                             table.Rows.Add(row);